As far as I was aware, it was preferable to put them snug against the board. That way, if they get bumped or jostled, it doesn't put stress on the solder joints.

I disagree. A cap sitting on the board that gets bumped can't flex on the leads. Instead of slightly bending the leads, all the force is amplified by the lever action created as the edge of the cap presses down on the board and UP on the leads. The result is the leads get pulled with a much greater force.

Leave enough space so the cap can rock a little. Hopefully it will rock out of the way before the edge touches the board.

It looks like the (-) pad was damaged on the missing capacitor to the left. Take a look to see if you need to repair that before soldering on the capacitor.

Your replacement cap more than likely is a snap cap, it is designed to hold itself in place against the circuit board. There is no reason at all for the capacitor to be mounter off the circuit board.

What in the world are you hitting it with to make all that force? Bending leads = cracking leads. Mount caps correctly flush to the board. To help secure large electrolytic cans from vibration, use a dab of neutral cure silicone rubber or epoxy resin on each side of the cap. It's never going anywhere then.

What Wayout said.

In addition, and this is important, most boards are mounted edge-wise, which means vibration is going to cause the leads to fatigue and if they do the can of the cap will contact the board with a gap to the lead. This results in a large lever-arm on the leads which is exactly what you do not want as vibration loads then have the potential to be magnified by that lever arm and the mass of the cap which can break the trace or through-hole plating.

IMHO mount flush and use a hot-glue gun to secure the top and bottom edges (in the "as-installed" position) of the can to the board. This will prevent vibration loads from being transmitted to the leads and yet leaves the can easily removable by cutting the room-temp hot glue with a razor blade should you need to do so in the future. I do not recommend using silicone rubber *anywhere* near electronics as even so-called "neutral cure" silicones may have some acid component to their formulation and "normal" ones are acetic-acid based and run the risk of eating your board over time.

Most neutral cure silicones are "Oxeme" cure and release oxemes and methyl alcohol. The former may cause corrosion of bare copper. Use alcohol cure such as GE RTV162 Electronic Grade Silicone Sealant. Non-corrosive to electronic metals, including copper and brass. Low odor cure, releasing an alcohol vapor from the sealant surface during cure.

There is really no reason to do anything more than solder these caps in position flush to the board just like they were originally, they aren't going to go anywhere. Most of the WPC89 boards haven't had any problems with capacitors that wasn't caused by using human error while attempting to replace them for no reason at all.

That being said, if you absolutely have to replace them, I would like to recommend using http://www.mouser.com/ProductDetail/Nichicon/LGU1E153MELB/?qs=%2fha2pyFadujh8EC7%2flpN3eaH9jrTTn63Sz3QtbhM8DCS5Z3bYOnVVw%3d%3d This is a snap-in cap with 30x35mm dimensions making it an ideal replacement for the originals and will only run you $4.00 each. This statement is not geared towards the OP as he has already purchased his caps, but more for anyone else reading this thread.

BTW, awesome desoldering job OP, looks very clean.

Excellent! I think you will be in great shape for years to come.